1. Field of the Invention
The invention relates to a technology for estimating a dust clogging amount on a filter that is used in a system that regulates the temperature of an electric storage device.
2. Description of Related Art
There is a technique in which a battery is cooled through supply of cooling air to the battery. In systems where cooling air is supplied to a battery, a filter may be provided in order to remove foreign matter that might be supplied to the battery along with the cooling air. If a filter is provided, it is necessary to grasp the clogging state of the foreign matter on the filter.
For example, Japanese Patent Application Publication No. 09-267646 (JP 09-267646 A) discloses the feature of determining the occurrence of clogging on an intake side or discharge side, on the basis of a number of revolutions of an intake fan and a discharge fan. Japanese Patent Application Publication No. 2001-136676 (JP 2001-136676 A) discloses the feature of measuring the temperature of a battery, and determining that clogging has occurred in an airflow passage when the measured temperature of the battery is higher than the expected temperature upon cooling of the battery.